/Engine/Source/Runtime/Engine/Public/MaterialHLSLGenerator.h
Returns the appropriate HLSLNode representing the givenUMaterialExpression. The node will be created if it doesn't exist. Otherwise, the tree will be updated to ensure the node is visible in the given scope Note that a givenUMaterialExpressionmay only support 1 of these node types, attempting to access an invalid node type will generate an error
const [UE::HLSLTree::FExpression](API\Runtime\Engine\HLSLTree\FExpression) * AcquireExpression ( [UE::HLSLTree::FScope](API\Runtime\Engine\HLSLTree\FScope) & Scope, int32 InputIndex, [UMaterialExpression](API\Runtime\Engine\Materials\UMaterialExpression) * MaterialExpression, int32 OutputIndex, const [UE::HLSLTree::FSwizzleParameters](API\Runtime\Engine\HLSLTree\FSwizzleParameters) & Swizzle )